1. Field of the Invention
The present invention relates to an automatic apparatus for the continuous treatment of leaf materials such as wafers of high-purity silicon semiconductors by reaction with gas plasma suitable for use in a production line of semiconductor elements or devices or, more particularly, to an apparatus for the treatment of wafer materials by gas plasma reaction having improved capacity for the treatment, which is provided with a plural number of adjoined gas plasma reaction chambers, the plural number of the reaction chambers being successively brought into operation by an automatic control means so as to transfer the wafer materials continuously.
2. Disclosure of the Prior Art
In recent years, etching treatment of semiconductor wafers and removal of photoresist by ashing in the semiconductor industry have been more and more widely performed by use of an apparatus for the treatment by gas plasma reaction. In the early stage of the development of such an apparatus, the treatment was undertaken batch-wise by holding a plural number of the wafers upright in a reaction tube and exposing them to the gas plasma simultaneously. Along with the recent trends wherein the patterns on the wafers are becoming finer and finer, larger and larger wafers are subjected to the plasma treatment and the production line is desired to be less labor-consuming, the batch-wise apparatus for the treatment as mentioned above has become obsolete due to the increasingly outstanding disadvantages. These include (1) the accuracy of working is insufficient, (2) the effect of the plasma treatment is not uniform from wafer to wafer, (3) the working efficiency is low due to the time-consuming hand works and (4) many of the wafers undergo various damages during the treatment. These disadvantages are more remarkable, in particular, in the treatment of the wafers having larger diameters.
In order to overcome the above described disadvantages, various attempts have been made hitherto proposing an apparatus for the continuous and automatic treatment of wafer materials with gas plasma. These automatic apparatuses for continuous gas plasma treatment have excellent characteristics of increased uniformity in the effectiveness of treatment and the improved reproducibility of extremely fine patterns as well as the decreased overall time taken for the treatment. Thus, they are widely used in the modern semiconductor industry as an apparatus capable of being in compliance with the requirements in the age of ultra-LSIs. There is, however, an eager desire for an apparatus with which further improvement of the productivity is obtained leading to lower and lower costs in the production of semiconductor devices.
In order to comply with such a desire, an attempt has been made to produce a method in which the capacity of the apparatus for treatment of, for example, gas plasma etching is obtained by increasing the temperature of treatment or by increasing the applied electric voltage. These methods are indeed effective in shortening the time of treatment with improved productivity but, on the other hand, are unavoidably accompanied by the disadvantages that, as the size of the wafers treated by the method becomes larger and larger, the variation in the effectiveness of the treatment increases resulting in lowered yield of the wafer products.
Most of the conventional automatic apparatus for the continuous plasma treatment of wafer materials are provided with a single gas plasma reaction chamber so that, when either one of the mechanism for the transfer of the wafers and the gas plasma reaction chamber is in operation, the other is necessarily alternately in a repose period. Therefore, improvement in the productivity of the plasma treatment process is usually obtained by the parallel installation and operation of a number of such unit apparatuses. This method of operation of the apparatuses is rather impractical because of the large expense for the installation of the apparatuses, the large space required for the installation thereof, the difficulties involved in the adjustment and conditioning of the individual apparatuses and the control of the operational conditions thereof.